Closed-circuit hydraulic propeller

ABSTRACT

The present invention provides closed-circuit hydraulic propeller used for the generation of thrust, or lift, force from the torque provided by a prime mover, or a motor, with said thrust, or lift, force being utilized in propelling, or lifting, a movable vehicle. In a preferred embodiment the closed-circuit hydraulic propeller comprises an outer casing; two inner-members; an intermediate body; a drive shaft; a rotor assembly including at least one central disk and a plurality of circumferentially arranged thrust, or lift, generating, blades; and an incompressible fluid completely filling the space enclosed within the casing. In operation, the incompressible fluid will circulate within the passages confined between the opposing surfaces of the casing, inner-members, and intermediate body due to its acceleration by the rotor blades, with the blades&#39; generated thrust force being transmitted to the propeller&#39;s casing through thrust bearing arrangement(s) Means for cooling the incompressible viscous fluid are also provided.

FIELD OF THE INVENTION

The present invention relates to a closed-circuit hydraulic propeller,and more particularly to a thrust, or lift, force generating hydraulicpropeller with which the torque provided by a prime mover, or a motor,can be utilized efficiently in generating thrust, or lift, force, withsaid generated force being used for propelling, or lifting, a movablevehicle.

BACKGROUND OF THE INVENTION

The use of properly shaped and properly angled foils for the efficientgeneration of lift forces on the wings of airplanes; the rotor blades ofhelicopters; and hydrofoils has been known in the art for decades, withLift/Drag ratios ranging between 10/1 and 65/1 being attainable.However, applying the same principal for the efficient conversion of thetorque provided by a prime mover, or a motor, into a thrust forcethrough the blades of propellers and ducted fans used for propellingdifferent types of vehicles is not practically feasible due to therelative drop in the efficiency of the thrust force generated by thefoils when operating in non-stagnant upstream working fluid conditions.

And thus, in spite of the well known high efficiency of properlydesigned, and properly angled; foils in generating lift, or thrust,forces, yet, their use for the efficient generation of thrust force todrive land vehicles, and the like, has been hindered by thesebefore-mentioned limiting factor.

SUMMARY OF THE INVENTION

The present invention provides a closed-circuit hydraulic propeller tobe used for the efficient generation of thrust, or lift, force,utilizing the torque provided by a prime mover, or a motor, with saidgenerated force being used in propelling, or lifting, a movable land,sea, or air vehicle.

The present invention also provides a closed-circuit hydraulic propellerwith which the amount of generated thrust, or lift, force may beflexibly changes within a relatively wide range.

In a preferred embodiment, the closed-circuit hydraulic propellercomprises: an assembly having a generally oval-shaped outer casingportion, a first inner-member portion, and a second inner-memberportion, the outer casing structurally supports and encloses otherpropeller elements positioned therein, and the outer surface of each ofthe inner-members partially defines a closed-circuit fluid flow passagewithin the propeller; a drive shaft supported for rotation in a givendirection inside the outer casing by an arrangement of bearings, andextending to a drive receiving end located outside the outer casing; arotor secured for rotation with the drive shaft and lying in a planenormal to the rotational axis of the drive shaft, said rotor includes atleast one central disk and a plurality of circumferentially arrangedthrust, or lift, generating, blades, each blade has an inner edgeattached to the central disk, an outer edge, a leading edge, and atrailing edge; and an incompressible viscous fluid completely fillingthe space enclosed within the outer casing.

In another preferred embodiment, the closed-circuit hydraulic propellerfurther comprises an intermediate-body fixedly attached to the outercasing and located intermediate of the outer casing and theinner-members, with the opposing surfaces of said intermediate-body andsaid outer casing defining an outer annular passage therebetween, andwith the opposing surfaces of said intermediate-body and saidinner-members defining an inner annular passage therebetween, with thesaid rotor blades being positioned for rotation within said innerannular passage, and with said intermediate body being configured toallow the flow of the said incompressible viscous fluid from said outerannular passage to the upstream inflowing portion of the inner annularpassage and from the downstream outflowing portion of the inner annularpassage to said outer annular passage.

In yet another preferred embodiment, the closed-circuit hydraulicpropeller further comprises a generally cylindrical shapedintermediate-body fixedly attached to the outer casing and locatedintermediate of the outer casing and the inner-members, with theopposing surfaces of said intermediate-body and said outer casingdefining an outer annular passage therebetween, and with the opposingsurfaces of said intermediate-body and said inner-members defining aninner annular passage therebetween, said inner annular passage has anupstream inflowing converging portion and a downstream outflowingdiverging portion, with said rotor blades being positioned for rotationwithin the said inner annular passage, and with the said intermediatebody being configured to allow the flow of said incompressible viscousfluid from said outer annular passage to said upstream inflowing portionof the inner annular passage and from said downstream outflowing portionof the inner annular passage to said outer annular passage.

In a preferred embodiment, each of the inner-members is generallyhourglass in shape. In another preferred embodiment, the downstreamoutflowing portion of the inner annular passage is provided with atleast one set of circumferentially arranged vanes to align the flow ofthe working fluid within the outflowing portion of the inner annularpassage during operation.

The number of the blades of the rotor may range between 2 and 36 blades,depending on the amount of thrust, or lift, force to be generated by thepropeller. Each two successive blades are separated from each other byan intervening gap, with the ratio between the mean width of each of thegaps and the mean Chord length of each of the blades (the Gap/Bladeratio or G/B ratio) being determined according to the desired degree ofdeceleration of the working fluid within the downstream outflowingportion of the inner annular passage during operation, noting that thedegree of deceleration will be proportional to the G/B ratio. In apreferred embodiment, the G/B ratio ranges between 0.5:1 and 3:1. Inanother preferred embodiment, the G/B ratio ranges between 1:1 and 2:1.

The successive parts of each blade are either designed with the sameangle of attack, or designed with gradually increasing angles of attackfrom the blade's outer edge to the blade's inner edge, so that thedownstream flow of the working fluid will be homogenized in terms oftotal pressure. The blades cross sectional configuration and the angleof attack, or the selected range of angles of attacks, is chosen toprovide optimum overall blade lift/drag ratio. Accordingly, in apreferred embodiment the angle of attack, or the angles of attacks ofthe successive parts of each blade, is/are chosen within a range ofangles lying anywhere between 2 degrees and 14 degrees, and in a morepreferred embodiment, the angle(s) of attack are chosen within a rangeof angles lying anywhere between 2 degrees and 10 degrees. Such designconsiderations are well known by people experienced in the Art.

In a preferred embodiment, means for cooling the working fluid areprovided. Said means may either provide passive cooling via a pluralityof cooling ribs on the outer surface of the propeller's casing, orprovide active cooling by forced air or fluid cooling arrangements.

The rotor is either manufactured as a whole by forging or casting, or,the central disk of the rotor is forged or casted separately, with eachblade, or each group of blades, being forged or casted separately,followed by assembling the rotor. Such manufacturing and assemblingtechniques are also well known by people experienced in the Art.

The thrust, or lift, force generated by the propeller's rotor istransmitted to the propeller's casing through one, or more than one,thrust bearing arrangements. Non limiting examples of thrust bearingarrangements for use include: fixed-geometry thrust bearings; andtilting pad thrust bearings.

In a preferred embodiment, the means provided for driving thepropeller's rotor comprises a prime mover, with the torque supplied bythe prime mover transmitted to the propeller's drive shaft eitherdirectly, or indirectly through a gear train arrangement. In anotherpreferred embodiment, the means provided for driving the propeller'srotor comprises an electric motor, with the torque supplied by it beingtransmitted to the propeller's drive shaft either directly, orindirectly through gear train arrangement, and with the electric motor'sdriving electric current being supplied from: at least one rechargeableelectricity storage system, e.g. an electric battery or anultracapacitor; a fuel cell; an electric generator driven by a primemover; or any combination thereof.

In a preferred embodiment, an even number of propellers is used, i.e.the propellers are arranged in one or more pairs, with each pair ofpropellers having counter-rotating rotors, to balance out the torqueeffect developed by their rotating components during operation.

DETAILED DESCRIPTION OF THE DRAWINGS

The description of the objects, features and advantages of the presentinvention, will be more fully appreciated by reference to the followingdetailed description of the exemplary embodiments in accordance with theaccompanying drawings, wherein:

FIG. 1 is a sectional view in a schematic representation of an exemplaryembodiment of a closed-circuit hydraulic propeller, in accordance withthe present invention.

FIG. 2 is a cross sectional view, taken at the plane of line 2-2 in FIG.1.

FIG. 3 is an enlarged view of two successive blades of the rotor of theembodiment of FIG. 1.

FIG. 4 is a sectional view in a schematic representation of anotherexemplary embodiment of a closed-circuit hydraulic propeller, inaccordance with the present invention.

FIG. 5 is a cross sectional view, taken at the plane of line 5-5 in FIG.4.

FIG. 6 is a sectional view in a schematic representation of anotherexemplary embodiment of a closed-circuit hydraulic propeller, inaccordance with the present invention.

FIG. 7 is a cross sectional view, taken at the plane of line 7-7 in FIG.6.

FIGS. 8A-D are schematic representation of different closed-circuithydraulic propellers-driving mechanism layouts in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a sectional view in a schematic representation of an exemplaryembodiment of a closed-circuit hydraulic propeller, in accordance withthe present invention.

The closed-circuit hydraulic propeller comprises: an assembly having agenerally oval-shaped outer casing portion (11), a first inner-memberportion (12), and a second inner-member portion (13), the outer casing(11) structurally supports and encloses other propeller elementspositioned therein, and the outer surface of each of the inner-members(12,13) partially defines a closed-circuit fluid flow passage within thepropeller; a drive shaft (14) supported for rotation in a givendirection inside the outer casing (11) by an arrangement of bearings(15,16) and extending to a drive receiving end (17) located outside theouter casing, with seal means (18) being provided between the opposingsurfaces of the shaft and the outer casing; a rotor (19) secured forrotation with the drive shaft (14) and lying in a plane normal to therotational axis of the drive shaft, said rotor includes a central disk(20) and a plurality of circumferentially arranged thrust, or lift,generating, blades (21), and as also shown in FIG. 2, which is a crosssectional view taken at the plane of line 2-2 in FIG. 1, each blade hasan inner edge (22) attached to the central disk (20), an outer edge(23), a leading edge (24), and a trailing edge (25); and anincompressible viscous fluid (26) completely filling the space enclosedwithin the outer casing (11).

In this embodiment, the number of the blades (21) of the rotor is 10blades, with each two successive blades being separated from each otherby an intervening gap (27), and as also shown in FIG. 3, which is anenlarged view of two successive blades of the rotor of the embodiment ofFIG. 1, the ratio between the mean width (28) of each of the gaps (27)and the mean Chord length (29) of each of the blades (21), i.e. theGap/Blade ratio or G/B ratio is 2:1. As described herein above, thenumber of the blades of the rotor may range between 2 and 36 blades,depending on the amount of thrust, or lift, force to be generated by thepropeller, with the used G/B ratio preferably lying anywhere between0.5:1 and 3:1, and more preferably lying anywhere between 1:1 and 2:1.

In this embodiment, the successive parts of each blade (21) have thesame angle of attack. However, in other preferred embodiments, theblades may be designed with gradually increasing angles of attack fromthe blades outer edges to the blades inner edges, so that the downstreamflow of the working fluid will be homogenized in terms of totalpressure. The blades cross sectional configuration and the selectedangle(s) of attacks is chosen to provide optimum overall blade lift/dragratio. Accordingly, in a preferred embodiment the angle of attack, orthe angles of attacks of the successive parts of each blade, is/arechosen within a range of angles lying anywhere between 2 degrees and 14degrees, and in a more preferred embodiment, the angle(s) of attack arechosen within a range of angles lying anywhere between 2 degrees and 10degrees. Such design considerations are well known by people experiencedin the Art.

The rotor (19) is either manufactured as a whole by forging or casting,or, the central disk (20) of the rotor is forged or casted separately,with each blade (21), or each group of blades, being forged or castedseparately, followed by assembling the rotor. Such manufacturing andassembling techniques are also well known by people experienced in theArt.

The thrust, or lift, force generated by the propeller's rotor (19) istransmitted to the propeller's casing (11) through one, or more thanone, thrust bearing arrangement (15). Non limiting examples of thrustbearing arrangements for use include: fixed-geometry thrust bearings;and tilting pad thrust bearings.

In this embodiment, the outer surface of the propeller's casing (11) isprovided with a plurality of cooling ribs (30) to cool the working fluid(26) during operation. However, in other preferred embodiments, theworking fluid may be actively cooled by a forced air or fluid coolingarrangements.

In operation, the working fluid (26) will be accelerated by the rotatingdownstream displacing surfaces of the blades (21), noting that thevectors of the accelerated working fluid by each two adjacent bladeswill be separated from each other due to the gap (27) between theblades. This separation between the vectors of the accelerated workingfluid along with the viscosity of the working fluid will lead todeceleration of the working fluid, along with partial damping of itsnon-axial vector components, so that the main bulk of the kinetic energyadded to the working fluid (26) through acceleration by the blades (21)will be dissipated and converted into heat.

The decelerated working fluid will be directed to the upstream portionof the fluid flow passage, where it will be accelerated by the effect ofthe suction force generated on the rotating upstream suction surfaces ofthe blades (21).

The net thrust, or lift, force provided by the closed-circuit hydraulicpropeller of the present invention will be equivalent to the totalthrust, or lift, force generated by the blades (21) minus the netreaction force acting on the walls defining the curved parts (31) of theinner walls of the casing (11), and thus, to maximize the net thrust, orlift, force we need to optimize the total thrust, or lift, forcegenerated by the blades (21) and minimize the net reaction force actingon the walls defining the curved parts (31) of the inner walls of thecasing (11).

Optimizing the total thrust, or lift, force generated by the blades (21)is provided by selecting the proper blades cross-sectional profile; theoptimum angle(s) of attack for use with the selected bladescross-sectional profile; and the proper type of incompressible viscousworking fluid (26) having relatively high boiling point and relativelyhigh dynamic viscosity.

Minimizing the net reaction force acting on the walls confining thecurved parts (31) of the fluid passage is provided by bringing down thekinetic energy within the working fluid (26) to a minimum before it isdeflected by the inner walls of the casing (11). This will depend on theconfiguration of the propeller's casing (11); the G/B ratio; and theviscosity of the working fluid (26).

FIG. 4 is a sectional view in a schematic representation of anotherexemplary embodiment of a closed-circuit hydraulic propeller, inaccordance with the present invention.

The closed-circuit hydraulic propeller comprises: an assembly having agenerally oval-shaped outer casing portion (51), a first inner-memberportion (52), and a second inner-member portion (53), the outer casing(51) structurally supports and encloses other propeller elementspositioned therein, and the outer surface of each of the inner-members(52,53) partially defines a closed-circuit fluid flow passage within thepropeller; an intermediate-body (54) fixedly attached to the outercasing and located intermediate of the outer casing (51) and theinner-members (52,53), with the opposing surfaces of saidintermediate-body and said outer casing defining an outer annularpassage (55) therebetween, and with the opposing surfaces of saidintermediate-body and said inner-members defining an inner annularpassage (56) therebetween, said inner annular passage has an upstreaminflowing converging portion (57) and a downstream outflowing divergingportion (58); a drive shaft (59) supported for rotation in a givendirection inside the outer casing (51) by an arrangement of bearings(60,61) and extending to a drive receiving end (62) located outside theouter casing, with seal means (63) being provided between the opposingsurfaces of the shaft and the outer casing; a rotor (64) secured forrotation with the drive shaft (59) and lying in a plane normal to therotational axis of the drive shaft, said rotor includes a central disk(65) and a plurality of circumferentially arranged thrust, or lift,generating, blades (66), said blades are positioned for rotation withinsaid inner annular passage (56), and as also shown in FIG. 5, which is across sectional view taken at the plane of line 5-5 in FIG. 4, eachblade has an inner edge (67) attached to the central disk (65), an outeredge (68), a leading edge (69), and a trailing edge (70); and anincompressible viscous fluid (71) completely filling the space enclosedwithin the outer casing (51), with said intermediate body (54) beingconfigured to allow the flow of said incompressible viscous fluid (71)from said outer annular passage (55) to said upstream inflowing portionof the inner annular passage (57) and from said downstream outflowingportion of the inner annular passage (58) to said outer annular passage(55).

In this embodiment, the number of the blades (66) of the rotor is 12blades, with each two successive blades being separated from each otherby an intervening gap, with the G/B ratio being 1.5:1, and with theother blade design parameters and other propeller's design andmanufacturing considerations being similar to the ones described hereinabove in reference to the embodiment of FIG. 1.

In operation, the working fluid (71) will be accelerated by the rotatingdownstream displacing surfaces of the blades (66), noting that thevectors of the accelerated working fluid by each two adjacent bladeswill be separated from each other due to the gap between the blades.This separation between the vectors of the accelerated working fluidalong with the viscosity of the working fluid and the divergingconfiguration of the downstream outflowing portion of the inner annularpassage (58) will lead to deceleration of the working fluid, along withpartial damping of its non-axial vector components. The axial lengthmeasurement of the downstream outflowing portion of the inner annularpassage (58) and its configuration are chosen to allow for optimumdeceleration of the working fluid, so that the main bulk of the kineticenergy added to the working fluid (71) through acceleration by theblades (66) will be dissipated and converted into heat.

The decelerated working fluid will be directed to the upstream inflowingportion of the inner annular passage (57) through the outer annularpassage (55), noting that the outer annular passage (55) slightlydiverges along the direction of the flow of the working fluid tocompensate for the deceleration of the working fluid within it.

Within the upstream inflowing portion of the inner annular passage (57)the working fluid (71) will be accelerated by the effect of the suctionforce generated on the rotating upstream suction surfaces of the blades(66), with the inflowing portion of the inner annular passage (57) beingconfigured to allow for smooth acceleration of the working fluids (71)within it.

The net thrust, or lift, force provided by the closed-circuit hydraulicpropeller of the present invention will be equivalent to the totalthrust, or lift, force generated by the blades (66) minus the netreaction force acting on the walls defining the curved parts (72) of theouter annular passage (55), and thus, to maximize the net thrust, orlift, force we need to optimize the total thrust, or lift, forcegenerated by the blades (66) and minimize the net reaction force actingon the walls defining the curved parts (72) of the outer annular passage(55).

Optimizing the total thrust, or lift, force generated by the blades (66)is provided by selecting the proper blades cross-sectional profile; theoptimum angle(s) of attack for use with the selected bladescross-sectional profile; and the proper type of incompressible viscousworking fluid (71) having relatively high boiling point and relativelyhigh dynamic viscosity.

Minimizing the net reaction force acting on the walls confining thecurved parts (72) of the fluid passage is provided by bringing down thekinetic energy within the working fluid (71) to a minimum before it isdeflected by the inner walls of the casing (51). This will depend on theconfiguration of the downstream outflowing portion of the inner annularpassage (58); the G/B ratio; and the viscosity of the working fluid(71).

FIG. 6 is a sectional view in a schematic representation of anotherexemplary embodiment of a closed-circuit hydraulic propeller, inaccordance with the present invention.

The closed-circuit hydraulic propeller comprises: an assembly having agenerally oval-shaped outer casing portion (81), a first inner-memberportion (82), and a second inner-member portion (83), the outer casing(81) structurally supports and encloses other propeller elementspositioned therein, and the outer surface of each of the inner-members(82,83) partially defines a closed-circuit fluid flow passage within thepropeller, with each of the inner-members being generally hourglass inshape; a generally cylindrical shaped intermediate-body (84) fixedlyattached to the outer casing and located intermediate of the outercasing (81) and the inner-members (82,83), with the opposing surfaces ofsaid intermediate-body and said outer casing defining an outer annularpassage (85) therebetween, and with the opposing surfaces of saidintermediate-body and said inner-members defining an inner annularpassage (86) therebetween, said inner annular passage has an upstreaminflowing converging portion (87) and a downstream outflowing divergingportion (88); a drive shaft (89) supported for rotation in a givendirection inside the outer casing (81) by an arrangement of bearings(90,91) and extending to a drive receiving end (92) located outside theouter casing, with seal means (93) being provided between the opposingsurfaces of the shaft and the outer casing; a rotor (94) secured forrotation with the drive shaft (89) and lying in a plane normal to therotational axis of the drive shaft, said rotor includes a central disk(95) and a plurality of circumferentially arranged thrust, or lift,generating, blades (96), said blades are positioned for rotation withinsaid inner annular passage (86), each blade has an inner edge (97)attached to the central disk (95), an outer edge (98), a leading edge,and a trailing edge; and an incompressible viscous fluid (99) completelyfilling the space enclosed within the outer casing (81), with saidintermediate body (84) being configured to allow the flow of saidincompressible viscous fluid (99) from said outer annular passage (85)to said upstream inflowing portion of the inner annular passage (87) andfrom said downstream outflowing portion of the inner annular passage(88) to said outer annular passage (85), and as also shown in FIG. 7,which is a cross sectional view taken at the plane of line 7-7 in FIG.6, the downstream outflowing portion (88) of the inner annular passageis provided with one set of circumferentially arranged vanes (100) toalign the flow of the working fluid (99) within the outflowing portionof the inner annular passage during operation.

In this embodiment, the number of the blades (96) of the rotor is 15blades, with each two successive blades being separated from each otherby an intervening gap, with the G/B ratio being 1:1, and with the otherblade design parameters and other propeller's design and manufacturingconsiderations being similar to the ones described herein above inreference to the embodiment of FIG. 1.

In operation, the working fluid (99) will be accelerated by the rotatingdownstream displacing surfaces of the blades (96), noting that thevectors of the accelerated working fluid by each two adjacent bladeswill be separated from each other due to the gap between the blades.This separation between the vectors of the accelerated working fluidalong with the viscosity of the working fluid and the divergingconfiguration of the downstream outflowing portion of the inner annularpassage (88) will lead to deceleration of the working fluid, along withpartial damping of its non-axial vector components. The axial lengthmeasurement of the downstream outflowing portion of the inner annularpassage (88) and its configuration are chosen to allow for optimumdeceleration of the working fluid, so that the main bulk of the kineticenergy added to the working fluid (99) through acceleration by theblades (96) will be dissipated and converted into heat. Further dampingof the residual non-axial components of the decelerated working fluidwill be provided by the set of the circumferentially arranged vanes(100) at the distal end of the outflowing portion of the inner annularpassage (88), which will also align the flow of the working fluid (99)parallel to the longitudinal axis of the propeller.

The decelerated working fluid flowing out of the vanes (100) will bedirected to the upstream inflowing portion of the inner annular passage(87) through the outer annular passage (85), noting that the outerannular passage (85) slightly diverges along the direction of the flowof the working fluid to compensate for the deceleration of the workingfluid within it.

Within the upstream inflowing portion of the inner annular passage (87)the working fluid (99) will be accelerated by the effect of the suctionforce generated on the rotating upstream suction surfaces of the blades(96), with the inflowing portion of the inner annular passage (87) beingconfigured to allow for smooth acceleration of the working fluids (99)within it.

The net thrust, or lift, force provided by the closed-circuit hydraulicpropeller of the present invention will be equivalent to the totalthrust, or lift, force generated by the blades (96) minus the netreaction force acting on the walls defining the curved parts of theouter annular passage (85), and thus, to maximize the net thrust, orlift, force we need to optimize the total thrust, or lift, forcegenerated by the blades (96) and minimize the net reaction force actingon the walls defining the curved parts of the outer annular passage(85).

Optimizing the total thrust, or lift, force generated by the blades (96)is provided by selecting the proper blades cross-sectional profile; theoptimum angle(s) of attack for use with the selected bladescross-sectional profile; and the proper type of incompressible viscousworking fluid (99) having relatively high boiling point and relativelyhigh dynamic viscosity.

Minimizing the net reaction force acting on the walls confining thecurved parts of the fluid passage is provided by bringing down thekinetic energy within the working fluid (99) to a minimum before itsflow out of the vanes (100). This will depend on the configuration ofthe downstream outflowing portion of the inner annular passage (88); theG/B ratio; and the viscosity of the working fluid (99).

FIGS. 8A-D are schematic representation of different closed-circuithydraulic propellers-driving mechanism layouts in accordance with thepresent invention.

As described herein above, the means provided for driving thepropeller's rotor may comprise a prime mover, with the torque suppliedby it being transmitted to the propeller's drive shaft either directly,or indirectly through gear train arrangement, or the propeller's rotoris driven by an electric motor, with the torque supplied by it beingtransmitted to the propeller's drive shaft either directly, orindirectly through gear train arrangement, and with the electric motor'sdriving electric current being supplied from at least one rechargeableelectricity storage system, e.g. an electric battery or anultracapacitor; a fuel cell; a prime mover driven electric generator; orany combination thereof.

In FIG. 8A, which is a schematic representation of a preferredembodiment of a closed-circuit hydraulic propeller-driving mechanismlayout, two closed-circuit hydraulic propellers (101,102) are used, eachdriven by a separate prime mover (103,104), wherein gas turbine enginesare used as the driving prime movers. This layout will be practical foruse in Vertical takeoff and landing (VTOL) aircrafts, as it allows fordistributing the used closed-circuit hydraulic propellers with theirdriving mechanisms around the fuselage, or below the wings, of theaircraft.

In FIG. 8B, which is a schematic representation of another preferredembodiment of a closed-circuit hydraulic propeller-driving mechanismlayout, two closed-circuit hydraulic propellers (105,106) are used, bothdriven by a common prime mover (107), with the torque supplied by theprime mover (107) being transmitted to the propellers (105,106) througha gear train arrangement (108). This layout will be practical for use inmedium and large sized land and sea vehicles, wherein only a prime moveris practically useful for providing the required amounts of torque, andwherein direct mechanical linkage between the propellers (105,106) andthe prime mover (107) is desirable to minimize the overall torquetransmission losses.

In FIG. 8C, which is a schematic representation of another preferredembodiment of a closed-circuit hydraulic propeller-driving mechanismlayout, two closed-circuit hydraulic propellers (111,112) are used, eachdriven by a separate electric motor (113,114), with the electric motors'driving electric current being supplied from at least one rechargeableelectricity storage system, e.g. an electric battery or anultracapacitor; a fuel cell; a prime mover driven electric generator; orany combination thereof (not shown in the drawing for simplicity).

In FIG. 8D, which is a schematic representation of another preferredembodiment of a closed-circuit hydraulic propeller-driving mechanismlayout, two closed-circuit hydraulic propellers (115,116) are used, bothdriven by a common electric motor (117), with the torque supplied by theelectric motor (117) being transmitted to the propellers (115,116)through a gear train arrangement (118), and with an intervening torquetransmission arrangement (119) being also provided between the electricmotor (117) and the gear train arrangement (118) to enable supplying thetorque provided by the electric motor (117) either to the closed-circuithydraulic propellers (115,116) or to another driving mechanism (120), asneeded. The electric motors' driving electric current is supplied fromat least one rechargeable electricity storage system, e.g. an electricbattery or an ultracapacitor; a fuel cell; a prime mover driven electricgenerator; or any combination thereof (not shown in the drawing forsimplicity).

This layout will be practical for use in Land vehicles wherein theforward movement of the vehicle constitutes the main part of its servicelife, while the backward movement of the vehicle is only neededoccasionally. Accordingly, the propulsion needed for the forwardmovement of the vehicle will be efficiently provided by theclosed-circuit hydraulic propellers (115,116), while the backwardmovement of the vehicle will be provided through another drivingmechanism, e.g. supplying the electric motor's torque to the wheels,with the torque transmission arrangement (119) enabling shifting theelectric motor's torque between the two driving mechanisms as needed.

Further objectives and advantages of the present invention will beapparent to those skilled in the art from the detailed description ofthe disclosed invention. The present discussion of illustrativeembodiments is not intended to limit the spirit and scope of theinvention beyond that specified by the claims presented hereafter.

1. A closed-circuit hydraulic propeller comprising: an assembly having agenerally oval-shaped outer casing portion, a first inner-memberportion, and a second inner-member portion, the outer casingstructurally supports and encloses other propeller elements positionedtherein, and the outer surface of each of the inner-members partiallydefines a closed-circuit fluid flow passage within the propeller; adrive shaft supported for rotation in a given direction inside the outercasing by an arrangement of bearings and extending to a drive receivingend located outside the outer casing; a rotor secured for rotation withthe drive shaft and lying in a plane normal to the rotational axis ofthe drive shaft, said rotor includes at least one central disk and aplurality of circumferentially arranged thrust, or lift, generating,blades, each blade has an inner edge attached to the central disk, anouter edge, a leading edge, and a trailing edge; and an incompressibleviscous fluid completely filling the space enclosed within the outercasing.
 2. The closed-circuit hydraulic propeller of claim 1, whichfurther comprises an intermediate-body fixedly attached to the outercasing and located intermediate of the outer casing and theinner-members, with the opposing surfaces of said intermediate-body andsaid outer casing defining an outer annular passage therebetween, andwith the opposing surfaces of said intermediate-body and saidinner-members defining an inner annular passage therebetween, with thesaid rotor blades being positioned for rotation within the said innerannular passage, and with the said intermediate body being configured toallow the flow of the said incompressible viscous fluid from the saidouter annular passage to the said upstream inflowing portion of theinner annular passage and from the said downstream outflowing portion ofthe inner annular passage to the said outer annular passage.
 3. Theclosed-circuit hydraulic propeller of claim 1, which further comprises agenerally cylindrical shaped intermediate-body fixedly attached to theouter casing and located intermediate of the outer casing and theinner-members, with the opposing surfaces of said intermediate-body andsaid outer casing defining an outer annular passage therebetween, andwith the opposing surfaces of said intermediate-body and saidinner-members defining an inner annular passage therebetween, said innerannular passage has an upstream inflowing converging portion and adownstream outflowing diverging portion, with the said rotor bladesbeing positioned for rotation within the said inner annular passage, andwith the said intermediate body being configured to allow the flow ofthe said incompressible viscous fluid from the said outer annularpassage to the said upstream inflowing portion of the inner annularpassage and from the said downstream outflowing portion of the innerannular passage to the said outer annular passage.
 4. The closed-circuithydraulic propeller of claim 1, wherein each of the said inner-membersbeing generally hourglass in shape.
 5. The closed-circuit hydraulicpropeller of claim 1, wherein the downstream outflowing portion of theinner annular passage is provided with at least one set ofcircumferentially arranged vanes to align the flow of the working fluidwithin the outflowing portion of the inner annular passage duringoperation.
 6. The closed-circuit hydraulic propeller of claim 1, whereinthe number of the blades of the said propeller's rotor ranges between 2and 36 blades.
 7. The closed-circuit hydraulic propeller of claim 1,wherein each two successive blades of the said propeller's rotor areseparated by an intervening gap.
 8. The closed-circuit hydraulicpropeller of claim 7, wherein the ratio between the mean width of eachof the said gaps and the mean Chord length of each of the said bladesranges between 0.5:1 and 3:1, and more preferably ranges between 1:1 and2:1.
 9. The closed-circuit hydraulic propeller of claim 1, wherein thesuccessive parts of each of the blades of the said propeller's rotor hasthe same angle of attack, with said angle of attack ranging between 2degrees and 14 degrees, and more preferably between 2 degrees and 10degrees.
 10. The closed-circuit hydraulic propeller of claim 1, whereinthe successive parts of each of the blades of the said propeller's rotorhas gradually increasing angles of attack from the blade's outer edge tothe blade's inner edge, with said angles of attack lying anywherebetween 2 degrees and 14 degrees and more preferably between 2 degreesand 10 degrees.
 11. The closed-circuit hydraulic propeller of claim 1,wherein seal means are provided between the opposing surfaces of thesaid drive shaft and the said outer casing.
 12. The closed-circuithydraulic propeller of claim 1, wherein means for cooling the saidincompressible viscous fluid are provided.
 13. The closed-circuithydraulic propeller of claim 12, wherein the said means provided forcooling the said incompressible viscous fluid comprises a plurality ofcooling ribs on the outer surface of the said propeller's outer casing14. The closed-circuit hydraulic propeller of claim 12, wherein the saidmeans provided for cooling the said incompressible viscous fluidcomprises a forced air or fluid cooling arrangement.
 15. Theclosed-circuit hydraulic propeller, of claim 1, wherein the thrust forcegenerated by the said propeller's rotor is transmitted to the saidpropeller's casing through at least one thrust bearing arrangement. 16.The closed-circuit hydraulic propeller of claim 1, wherein the saidpropeller's drive shaft is driven by at least one prime mover.
 17. Theclosed-circuit hydraulic propeller of claim 16, wherein the torquesupplied by the said prime mover is transmitted to the said propeller'sdrive shaft through a gear train arrangement.
 18. The closed-circuithydraulic propeller of claim 1, wherein the said propeller's drive shaftis driven by at least one electric motor.
 19. The closed-circuithydraulic propeller of claim 18, wherein the torque supplied by the saidelectric motor is transmitted to the said propeller's drive shaftthrough a gear train arrangement.
 20. The closed-circuit hydraulicpropeller of claim 18, wherein the driving electric current for the saidelectric motor is supplied from at least one rechargeable electricitystorage system; a fuel cell; an electric generator driven by a primemover; or any combination thereof.